A gesture sensor is a human interface device that enables the detection of physical movement without the user actually touching the device within which the gesture sensor resides. The detected movements can be subsequently used as input commands to the device. In some applications, the device is programmed to recognize distinct non-contact hand motions, such as left to right, right to left, up to down, down to up, diagonally up to left, diagonally up to right, in to out, and out to in hand motions. Gesture sensors have found popular use in handheld devices, such as tablet computing devices and smartphones, and other portable devices, such as laptops. Gesture sensors are also being implemented in video game consoles that detect the motion of a video game player.
FIG. 1 illustrates a conventional gesture sensing system 100. As shown in FIG. 1, the system 100 includes an illumination source 102 for outputting light 106 and a light sensor 104 for receiving light. In operation, the illumination source 102 is turned on and off, or flashed, in succession in order for the sensor 104 to obtain spatial information about an object 99 proximate the light sensor 104. Specifically, the light sensor 104 is able to receive a portion of the light 106 from the illumination source 102 that has reflected off of the object 99 and back to the light sensor 104. Based on this received reflected light 108, the movement or gesture of the object 99 is able to be determined. FIG. 2 illustrates a signal diagram 200 corresponding to the gesture sensor system 100 shown in FIG. 1. Specifically, as shown in FIG. 2, as the illumination source signal 202 turns on from time t0 to t1 and time t2 to t3 (e.g. the illumination source 102 flashes) the reflected light 108 received by the light sensor 104 causes the light sensor signal 204 to increase above the measured ambient light level 210 wherein the increase corresponds to the spatial characteristics of the object 99. As a result, movement or gestures of the object 99 are able to be determined based on the measured increases over time.
However, a disadvantage of these conventional systems 100 is the amount of noise on the sensor 104 of the system caused by the ambient light 110. In particular, as the ambient light level 210 increases the minimum detectable signal increases thereby reducing the resolution and effectiveness of the system 100. As a result, many of these systems are forced to employ costly noise cancellation elements in order to cancel out the noise caused by the ambient light. With ever decreasing device size, additional components are undesirable.